Resources

Background

One of the important contributors to health risk from air pollution, perchloroethylene is a non-flammable, colorless, dense liquid at room temperature. Perchloroethylene vapors are irritating to the eyes and respiratory tract. It
is also a central nervous system depressant. Chronic exposure to perchloroethylene may cause kidney, liver dysfunction,
and neurological effects. California has determined under Assembly Bill 1807 and Proposition 65 that perchloroethylene
is a cancer-causing compound. The Air Resources Board (ARB) has taken regulatory actions to reduce perchloroethylene
emissions.

Perchloroethylene is a volatile organic hydrocarbon that is used as a solvent primarily in dry cleaning operations.
Perchloroethylene is also used in degreasing operations, paints and coatings, adhesives, aerosols, specialty chemical
production, printing inks, silicones, rug shampoos, and laboratory solvents. Stationary sources account for 82%
of the statewide emissions. Volatilization from dry cleaned garments is the major indoor perchloroethylene source.
There are no natural sources of perchloroethylene.

The Air Resources Board (ARB) adopted a perchloroethylene control measure in 1993 on dry cleaning facilities, which
requires closed-loop machines used on dry cleaning operations and provides training to dry cleaning operators.
The Air Resources Board (ARB) adopted another control measure in 2000 to eliminate the use of perchloroethylene
in degreasers for automotive maintenance and repairing. In the 1990s, the ambient perchloroethylene level showed
a steady downward trend, based on the statewide annual average. The 2000 statewide ambient perchloroethylene concentration
was approximately 58% lower than that in 1990.

Ambient Monitoring Results

Ambient levels of perchloroethylene are routinely monitored at approximately twenty sites in the California air toxics monitoring network. The statewide average concentration of perchloroethylene during 1998-2000 was 0.1 ppb
(parts per billion), based on values ranging from 0.005 ppb to 2.2 ppb. Relative to the statewide average, the
Los Angeles County region was 200% higher, with an average concentration of 0.30 ppb for the same time period.

The ambient monitoring results at Hollenbeck are provided here:

A graph comparing the monthly summaries of perchloroethylene at the community
with historical statewide and regional levels

Cancer Risk

Cancer risk is the number of excess cancer cases among a million people if the people are exposed to levels of a toxic air pollutant over 70 years. Perchloroethylene represents approximately 2% of the potential cancer risk of the nine measured compounds, excluding diesel particulate matter. Perchloroethylene represents less than 1%
of the potential cancer risk of the nine measured compounds and the estimated diesel particulate matter.